Sewing machines comprising auxiliary feed devices as briefly outlined in the foregoing are known in the art. They serve to achieve a nearly fully automated joining of textile material or the like to be sewn together. Such pieces can be sleeves, trouser-leg fabric workpieces or similar garment pieces.
In such arrangements care has to be taken to ensure proper advancing or transporting of the parts to be sewn together in the sewing machine with respect to the sewing machine. Thus, the parts have to be guided with relation to the needle or, in other words, in a position which will ensure formation of a desired stitch pattern or contour.
This is achieved by guide means which exert a self-guiding effect on the parts to be sewn, which avoid wandering in a sideway direction of the parts and which will attain stretching of the material by attaching the parts to movable carriers.
Sewing machines equipped with a relatively small number of feed and control devices, to form a sewing station as mentioned in the foregoing, normally require only one operator whose responsibility is restricted to ensuring the accurate positioning of parts at a loading station. While it would appear that a streamlined operation is thus achieved, the cyclic nature of the reciprocating motion, i.e. the advancing and retracting of the carrier to and from the sewing machine, has been an obstacle in achieving a truly efficient operation.
The drawback of the devices of the prior art becomes especially apparent when working with lengthy garment pieces. Thus, considerable down time will occur because of the intermittent operation of such systems.
In German utility model (Gebrauchsmuster) DGBM 7438034 it has been suggested, for example, to utilize two carriers or clamps in alternating fashion. In this proposal the down time is reduced or eliminated because one carrier is loaded and then moved into the working position with respect to the sewing machine while the second carrier is loaded and brought into position for advancement to the sewing machine.
Such an operation can be carried out with a single carrier when provision is made to arrange the parts to be sewn together in assemblies which can readily be sewn together on the sewing machine. This preparatory step is carried out while the carrier returns to the loading station. The assemblies to be sewn together by the sewing machine are then transferred to the carrier by means of a transfer device. During the transfer a short period of down time is incurred.
Also, the sewing facilities that are known in the art and offer a relatively continuous operation require numerous moving parts and thus tend to be expensive and difficult to operate.